Cytotoxicity and immunomodulating characteristics of labdane diterpenes from Marrubium cylleneum and Marrubium velutinum

From the aerial parts of Marrubium cylleneum, one labdane nor-diterpene has been isolated together with two labdane diterpenes, hitherto not known as natural products. Several diterpenoids from both plants were tested for their cytotoxic effect against various cancer cell lines and their immunomodulating potential in human peripheral blood mononuclear cells. Our results show a differential cytotoxicity of some compounds, as well as their ability to improve selected lymphocyte functions.